Electric Propulsion Research Articles

Efficiency scaling of inductively coupled plasmas for radio frequency propulsion systems

AbstractA generalized inductively coupled plasma (ICP) efficiency model is derived, which may be used to predict plasma generation efficiency with many types of radio frequency (RF) electric propulsion system. The analytical ICP discharge model is used to examine device scaling, and investigate trends in ICP performance as a function of geometry and system inputs. The ICP efficiency model is applied to an analytical RF cathode model to predict device behavior. Results from the updated RF cathode model show improvements in agreement with experimental data.

Dynamic Response Control Strategy for Parallel Hybrid Ships Based on PMP-HMPC

With increasingly stringent emission regulations, various clean fuel engines, electric propulsion systems, and renewable energy sources have been demonstratively applied in marine power systems. The development of control strategies that can effectively and efficiently coordinate the operation of multiple energy sources has become a key research focus. This study uses a modular modeling method to establish a system simulation model for a parallel hybrid ship with a natural gas engine (NGE) as the prime mover, and designs an energy management control strategy that can run in real time. The strategy is based on Pontryagin’s minimum principle (PMP) for power allocation, and is supplemented by a hybrid model predictive control (HMPC) method for speed-tracking control of the power system. Finally, the designed strategy is evaluated. Through simulation and hardware-in-the-loop (HIL) experimental validation, results compared with the Rule-based strategy indicate that under the given conditions, the SOC final value deviation from the initial value is reduced from 11.5% (in the reference strategy) to 0.39%. The system speed error integral is significantly lower at 39.06, compared to 2264.67 in the reference strategy. While gas consumption increased slightly by 2.4%, emissions were reduced by 3.2%.

Design and performance evaluation of a spiral bar precision weeding mechanism for corn fields.

This paper focuses on addressing the limitations of existing mechanical weeding methods for corn plants by introducing a spiral tendon-type precision weeding device specifically designed for corn fields. The study encompasses mechanical design and theoretical analysis to determine the overall structure, component parts, application scenarios, operation modes, and working principles of the device. The force applied to the spiral tendon weeding cutter head, a crucial working component of the device, is analyzed, along with its motion characteristics. This analysis allows for the calculation of the force required for the spiral tendon to penetrate the soil, as well as the determination of its trajectory and speed in the soil. The desired motion pattern of the weeding cutter head is considered in determining the contour shape of the inner cylinder track and its cooperation mode with the roller follower. Furthermore, the design and optimization of the circulation groove track are conducted to derive the key parameters of the track. A prototype is then constructed based on the proposed structural design and parameter optimization scheme. Soil bin tests are performed to evaluate the device's performance. The optimal combinations of working parameters are determined as follows: a 70-mm depth of the weeding cutter head into the soil, a movement speed of 80mm/s, and an output thrust of the electric actuator of 180N. Under these conditions, the device achieves a weed removal rate exceeding 95% with a 3% wounding rate, demonstrating stable operational performance.

Advanced Design of Naval Ship Propulsion Systems Utilizing Battery-Diesel Generator Hybrid Electric Propulsion Systems

As advanced sensors and weapons require high power, naval vessels have increasingly adopted electric propulsion systems. This study aims to enhance the efficiency and operability of electric propulsion systems over traditional mechanical propulsion systems by analyzing the operational profiles of modern naval vessels. Consequently, a battery-integrated generator-based electric propulsion system was selected. Considering the purpose of the vessel, a specification selection procedure was developed, leading to the design of a hybrid electric propulsion system (comprising one battery and four generators). The power management control technique of the proposed propulsion system sets the operating modes (depending on the specific fuel oil consumption of the generators) to minimize fuel consumption based on the operating load. Additionally, load distribution control rules for the generators were designed to reduce energy consumption based on the load and battery state of charge. MATLAB/Simulink was used to evaluate the proposed system, with simulation results demonstrating that it maintained the same propulsion performance as existing systems while achieving a 12-ton (22%) reduction in fuel consumption. This improvement results in cost savings and reduced carbon dioxide emissions. These findings suggest that an efficient load-sharing controller can be implemented for various vessels equipped with electric propulsion systems, tailored to their operational profiles.

A Comparative Analysis and Scoping Review of Soft–Rigid and Industrial Parallel Rigid Grippers

In this research, it is aimed to present a comparative analysis of soft–rigid industrial parallel rigid grippers to compare their technical capabilities and assess the potential for soft–rigid grippers to address the challenge of grasping fragile objects with various shapes and sizes. In this research, 24 soft–rigid grippers are first identified through a scoping review using the Web of Science database, capturing their technical features and performance. Providing a variable stiffness grasp (n = 9, 37.5%) and a limited grasp capability (n = 8, 33.3%) is the most common advantage and challenge, respectively, of soft–rigid grippers. Pneumatic actuators (n = 12, 50.0%), followed by tendon‐driven electric rotary actuators (n = 9, 37.5%), are the predominant actuators used for soft–rigid grippers. Soft–rigid grippers are found to have a lower output force‐to‐weight ratio (n = 9, median , standard deviation (σ) = 15.17) in comparison to industrial parallel rigid grippers (n = 63, , ), but can provide a larger range of motion (n = 20, , ). This is the first quantitative comparative analysis between industrial parallel rigid and soft–rigid grippers, enhancing the understanding of their status and prospects in industrial applications. Herein, a common approach is proposed to standardize reporting to facilitate benchmarking between research‐based and industrial grippers and highlight controlling soft–rigid grippers is an underexplored area that can enhance the technology's performance.

Application of torque observer based on belief rule base to power redistribution process

When navigating in ice zones, broken ice can be drawn into the propeller by the wake current, significantly altering the propeller load and causing severe fluctuations in the power grid of electrical propulsion ship. To address this issue, this paper presents two kinds of power redistribution control (PRC) strategies, which utilises the dynamic feedback from the ship's generator sets to the electric propulsion system to improve the frequency control. The PRC strategy #2, which receives feedback from generator's torque deviation, has better control effect than PRC strategy #1 with feedback from speed deviation. Since the accuracy of the estimated mechanical torque directly affects the control effect of strategy #2, this paper designs a torque observer based on the Belief Rule Base (BRB) by matching the PRC strategy to regulate the grid frequency in real-time. Given the power grid's fluctuations primarily caused by aft propellers, the power will be partly redistributed to the bow thruster to stabilise the ship's grid. Experiments show that this method can maintain the stability of the grid frequency by quickly correcting the power distribution during the process of sudden shedding propeller load.

A High Performance Nonlinear Longitudinal Controller for Fixed-Wing UAVs Based on Fuzzy-Guaranteed Cost Control

Unmanned aerial vehicles (UAVs) have garnered more attention across various industries in recent years, leading to significant development in their design and application globally. Due to the high coupling between UAV states, model uncertainties, and various disturbances, precise longitudinal control of UAVs remains a significant research challenge. Oriented for the speed and altitude control of an electrical-powered fixed-wing UAV, this paper introduces a new control strategy based on the fuzzy guaranteed cost control (F-GCC) technique, which results in a nonlinear longitudinal state feedback control law with strict stability criterion, effectively addressing the issue of state coupling. Moreover, the strategy also includes a thrust estimation model of the electrical propulsion system to significantly reduce the nonlinearity, simplifying the controller design while effectively preserving tracking control performance. Through numerical validation, the UAV longitudinal nonlinear controller designed using the F-GCC technique offers better transient response and stronger robustness than the traditional linear and ADRC controllers.

Aerodynamic optimisation of flat-upper-surface wing

Purpose The paper aims to optimise several concepts of the flat-upper-surface wing that could install the largest possible number of photovoltaic cells and test them in flight. A wing ideal flat upper surface was necessary to provide the same lighting conditions for each tested cell. Design/methodology/approach The optimised wings were built based on a developed family of airfoils having 75% of their upper surface flat. Within the developed parametric model of the wings, the design parameters described the spanwise distribution of base airfoils. Maximisation of the endurance factor was assumed as the main objective. The aerodynamic properties of optimised wings were evaluated using a panel method coupled with boundary layer analysis. Findings The paper proves that it is possible to design wings with 75% of their upper surface perfectly flat, which are also characterised by good aerodynamic properties. Practical implications The research conducted will allow designing an experimental unmanned aerial vehicle dedicated to investigating the properties of electrical propulsion systems at various altitudes. Data obtained in these investigations will help in the development of future generations of electric-propulsion aircraft. Originality/value The innovative wings, developed within the research are unique due to their unusual geometric and aerodynamic properties. They have 75% of their upper surface perfectly flat. That makes them ideal for testing various photovoltaic cells in flight. The biggest challenge was to design the wings so that their specific geometric features did not impair their aerodynamic properties. The paper proves that this challenge has been fully overcome.

Using magnesium hydride as the future dual-mode propellant for spacecraft: A simulation investigation

A dual-mode propulsion system stands as the important viable pathway for future multi-purpose deep space missions by the spacecraft, encompassing both nuclear thermal propulsion and nuclear electric propulsion. H2 and Mg emerge as potential mediums for nuclear thermal propulsion and nuclear electric propulsion, respectively, with the possibility of utilizing a single material, magnesium hydride (MgH2), to serve both purposes. However, how to release hydrogen completely and effectively in high hydrogen desorption pressure while retaining magnesium is the key problem. In this work, we proposed a novel MgH2 storage tank for zero gravity environments and investigated its hydrogen desorption process at high pressures of 4 ∼ 8 MPa using simulation, which is crucial for the hydrogen supply of nuclear thermal propulsion. We examined the effects of hydrogen desorption pressure, inlet temperature, and flow velocity of argon (Ar) on the desorption process. The simulation results indicated complete decomposition of MgH2 can be realized under 4 ∼ 8 MPa at 873 K. Moreover, the desorption pressure, inlet temperatures, and high flow velocities of Ar are suggested as 4 MPa, 773 ∼ 785 K, and 45 ∼ 100 m s−1 to achieve an average hydrogen desorption rate per unit thermal power of ≥ 20 mgH2 s−1. This work marks the first confirmation that MgH2 can decompose into H2 and Mg under high hydrogen desorption pressure at suitable thermal power, paving the way for its application as the hydrogen and Mg storage media in the dual-mode propulsion system of spacecraft.

Enhanced Output Performance of Two-Level Voltage Source Inverters Using Simplified Model Predictive Control with Multi-Virtual-Voltage Vectors

Interest in electric propulsion ships has garnered attention to reduce ship exhaust emissions. This has sparked extensive research on inverters. While two-level voltage source inverters are commonly utilized in small- and medium-sized ships owing to their simple structure and cost-effectiveness, they have limitations, such as high switching losses and reduced output performance. To address these issues, a model predictive control technique based on virtual voltage vectors is proposed in this study. Conventional two-level voltage source inverters are restricted to using only eight voltage vectors, which limits their output performance. By incorporating virtual voltage vectors, similar performance to multilevel converters can be achieved. The proposed technique involves a pre-voltage selection method that enhances output performance without increasing computational load. Through simulation and experiments, improved output current THD and current error were observed under various load conditions. This showcases the potential for enhancing the efficiency and performance of electric propulsion ships.

Influence of cyclic ignition and steady-state operation on a 1–2 A barium tungsten hollow cathode

Booming low-power electric propulsion systems require 1–2 A hollow cathodes. Such cathodes are expected to go through more frequent ignitions in the low orbit, but the impact of cyclic ignitions on such 1–2 A barium tungsten hollow cathodes with a heater was not clear. In this study, a 12,638-cyclic ignition test and a 6,000 hour-long life test on two identical cathodes were carried out. The discharge voltage of the cathode and the erosion of the orifice after cyclic ignition were all larger than that of the cathode after stable operation. This indicated that the impact of cycle ignition on the discharge performance of a low current BaO-W cathode with a heater was higher than that of stable operation. The results of the ion energy distribution function measured during the ignition period indicated that the main reason for the orifice expansion was ion bombardment. Therefore, it was necessary to pay attention to the number of ignitions for the lifetime of this kind of cathode.

A simplified automated approach for a preliminary safety assessment of distributed electric and hybrid propulsion systems

AbstractTo reduce the environmental impact of future aircraft, the usage of disruptive hybrid electric propulsion systems, in conjunction with distributed propulsion systems, is envisioned. The complexity of those novel powertrain concepts increases significantly. Besides nominal system characteristics, this particularly applies for off-nominal behaviour and consequences. As the safety impact on aircraft level is not always obvious, the suitability of a given component failure rate has to be analysed already in a preliminary design stage. Within this work, a method shall be introduced that allows a simplified automated safety assessment of any powertrain architecture. All relevant combinations of single and multiple failures are identified and a combined failure rate is derived. Thereafter, the impact of single and multiple component failures is evaluated on aircraft level. A selection of metrics for top-level-aircraft functions is used to implement an impact-driven analysis for each relevant failure case. The metrics used assess the adverse effects on climb performance, lateral controllability and range degradation. For all failure combinations, these effects can be validated against requirements imposed on the configuration. The possibility to formulate failure rate-related requirements follows the idea to target an equivalent level of safety compared to existing regulations, independently of the nature of the failure scenario. Results of this study show the necessity for a reevaluation of the configurations assessed, either regarding their architecture or the assumed component failure rate. The method allows an early detection of configuration-specific shortcomings of complex powertrain architectures already in a preliminary aircraft design stage.

Analysis of azimuthal electron current driving by rotating magnetic field in field-reversed configuration electric propulsion

Field-reversed configuration electric propulsion is an advanced space electromagnetic propulsion technology with significant application prospects but poor thrust performance. To delve into the intrinsic physical mechanisms, a model of the rotating magnetic field penetrating into the plasma and azimuthal electron current driving was developed. The simulation results show that rotating magnetic field strength, frequency, and initial seed plasma density are the key factors that exist as an optimal threshold. Specifically, the rotating magnetic field feed current (i.e., magnetic field strength) was not less than 1000 A, the rotating magnetic field frequency was ∼200–300 kHz, and the plasma density was approximately 1 × 1018 m−3 order of magnitude.

Study on Coordination of Different Types of DC Superconducting Current Limiter and DC Circuit Breaker for Electric Propulsion Aircraft

Study on Coordination of Different Types of DC Superconducting Current Limiter and DC Circuit Breaker for Electric Propulsion Aircraft

Bidirectional scanning acquisition of inter-satellite laser links for space gravitational wave detection mission.

Space gravitational wave detection requires establishing laser links between distributed spacecraft for interferometry. Inter-satellite laser link acquisition is an essential step in this process. Considering the spacecraft's miniaturization and reliability, a bidirectional scanning acquisition method is proposed using only field emission electric propulsion and quadrant photodetector. This method does not require additional acquisition sensors and actuators. To improve efficiency while ensuring the acquisition success rate, a constant angular velocity Archimedean spiral scanning guidance law is proposed, and the critical parameters that influence acquisition time and success rate are analyzed. Monte Carlo simulations show that the method can ensure an acquisition success rate of over 90%. Compared with constant linear velocity Archimedean spiral scanning, this method can reduce the acquisition time required to achieve the same success rate by 15%.

Design of ION Thruster

Ion thrusters represent a significant advancement in electric propulsion, enhancing fuel efficiency by accelerating ions for thrust generation. These systems, demonstrated in missions such as Deep Space 1 and Dawn, facilitate substantial velocity changes with minimal propellant, making them suitable for long-duration space missions. This paper outlines the design of an ion thruster aimed at achieving a thrust of 0.2 Newton, focusing on the use of xenon as the propellant and employing highvoltage grids for ion acceleration. Key design aspects include an efficient power supply delivering at least 26 W, effective thermal management, and the integration of control systems. Performance metrics target a specific impulse of 3,000 seconds and a thrust-to-power efficiency ratio greater than 0.5. Through detailed calculations, including arc distance, flow configuration and velocity analyses and testing using different materials, this study identifies optimal configurations for thrust generation. The developed ion thruster is tailored for small satellites (700-800 kg) to enhance trajectory control and station-keeping, underscoring the importance of ion propulsion in modern space exploration

Comparison of Propulsion Options for Interplanetary Missions

This paper investigates propulsion options and trajectory designs for a manned mission from Earth to Mars, followed by a mission to Ceres. It evaluates various propulsion technologies, including traditional chemical propulsion, nuclear thermal propulsion (NTP), and electric propulsion systems such as ion thrusters and Hall effect thrusters. The analysis highlights the limitations of chemical propulsion in terms of energy efficiency and payload capacity while underscoring the potential of NTP to reduce travel time and improve crew safety due to its higher specific impulse. The study also examines the feasibility of solar and nuclear electric propulsion, focusing on their high efficiency and suitability for extended missions, and considers innovative concepts like solar sails and fusion propulsion for their theoretical advantages in thrust and velocity. Low-thrust trajectories are analyzed for their ability to minimize overall delta-V requirements, which is essential for mission success. For the Mars mission, chemical propulsion systems currently under development are evaluated alongside electric propulsion powered by nuclear reactors, which could significantly reduce travel times and propellant needs. The additional challenges of propelling a spacecraft to Ceres, a more distant destination in the asteroid belt, shift the focus to electric propulsion options, particularly advanced nuclear-electric systems, which offer the potential to enable human exploration within a reasonable timeframe. The paper concludes that the optimal propulsion system for a manned mission to Mars and Ceres requires balancing travel time, technical feasibility, and crew safety, emphasizing the necessity for further development of advanced electric propulsion technologies to facilitate ambitious human deep-space exploration.

Enhanced voltage ripple control in electric vehicle propulsion systems using a dual-inverter-fed open-end-winding motor

Enhanced voltage ripple control in electric vehicle propulsion systems using a dual-inverter-fed open-end-winding motor

Data-driven digital marketing and battery supply chain optimization in the battery-powered aircraft industry through case studies of Rolls-Royce’s ACCEL and Airbus's E-Fan X Projects

This paper investigates the interplay between data-driven digital marketing strategies and battery supply chain optimization in the battery-powered aircraft industry, with a focus on Rolls-Royce's ACCEL and Airbus's E-Fan X projects. As the electric aircraft market emerges, these companies face the dual challenge of promoting technological advancements to a skeptical audience while navigating complex supply chain requirements. The study explores how data analytics and targeted content marketing are employed to enhance stakeholder engagement, build consumer trust, and communicate the benefits of electric aviation. By leveraging digital platforms, Rolls-Royce and Airbus effectively highlight key aspects such as battery performance, sustainability, and the safety of electric propulsion, addressing both technical and consumer concerns. Concurrently, the research delves into the intricacies of battery supply chain optimization, examining the processes involved in sourcing high-energy-density batteries, ensuring quality control, and adhering to regulatory standards. Advanced supply chain management techniques, including predictive analytics and real-time monitoring, are analyzed for their role in streamlining procurement and manufacturing processes. The integration of these strategies within digital marketing campaigns demonstrates how each company positions itself as a leader in the industry, emphasizing technological innovation and reliability. This study aims to provide a comprehensive understanding of how digital marketing and supply chain optimization are not only critical for promoting the adoption of electric aircraft but also for overcoming market skepticism and ensuring operational efficiency. By presenting case studies of two pioneering projects, ACCEL and E-Fan X, the research highlights best practices and strategic approaches that can guide other companies in the industry. The findings underscore the importance of a synergistic approach where digital marketing is informed by supply chain realities, creating a transparent and trustworthy narrative for consumers and stakeholders. Ultimately, this paper contributes to the discourse on how emerging technologies in aviation can be successfully marketed and operationalized, offering insights into the effective use of digital marketing and supply chain management in the rapidly evolving electric aircraft sector.

Satellite surface charging in LEO with ProPIC

ProPIC is a fully kinetic particle-in-cell (PIC) solver developed for space electric propulsion. This work has extended its capabilities to simulate satellite surface charging and wake generation in low Earth orbit (LEO). A novel scaling approach has been implemented, decreasing computational cost by more than one order of magnitude. The methodology and scaling approach have been verified against the revised orbital-motion-limited theory. The surface charging and wake generation in LEO have been examined for a satellite that is more complex and larger than what is typically handled with a fully kinetic PIC approach in LEO, particularly due to the presence of large solar panels. Notably, the simulated wake can be used to identify the optimal position for the plasma diagnostic sensor that minimizes interference with the wake. Moreover, despite not being a failure risk, the attitude greatly influences the surface charging of a satellite with large solar arrays installed parallel to the satellite speed vector. The study suggests that, for high positive pitch angles (>45∘), the surface charging of the solar panels can increase by as much as 75% compared to low negative pitching cases. Additionally, the study highlights that the pitch angle and satellite envelope along the motion direction significantly influence the potential gradients on the solar panels.